The present disclosure relates to a communication module.
It is known that some communication modules for performing wireless transmission between wireless data communication devices support frequency bands for a plurality of different communication standards. For example, Japanese Unexamined Patent Application Publication No. 2006-237978 discloses a multiband high-frequency module that provides wireless transmission in the 5 GHz frequency band, which is used in wireless local area networks (LANs), and wireless transmission in the 2.4 GHz frequency band, which is used in wireless LANs or Bluetooth (registered trademark).
The 5 GHz frequency band is adjacent to the frequency of the second harmonic of the 2.4 GHz frequency band. Thus, it is important in, in particular, a communication module supporting both frequency bands to maintain isolation between communication channels of the frequency bands. In this regard, Japanese Unexamined Patent Application Publication No. 2006-237978 discloses an improvement in isolation characteristics between an output terminal for a reception signal and an input terminal for a transmission signal of one of the frequency bands. However, there is no mention of an improvement in isolation characteristics between input terminals for transmission signals of different communication systems. In the configuration disclosed in Japanese Unexamined Patent Application Publication No. 2006-237978, therefore, for example, if input terminals for transmission signals of different frequency bands are formed close to each other in order to support the reduction in the size of a communication module, the isolation characteristics between the input terminals can deteriorate.